VHT Sig:X Amplifier Head Review

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NEARLY 20 YEARS AGO, VHT paved the road for the modern “super amp” category by combining a high-power output stage with three fully independent channels and an advanced switching system—along with a host of other groundbreaking features. The Sig:X extends that legacy with a truckload of fine-tuning features and enhanced versatility, and it’s sure to attract a lot of attention from a wide range of players.


WITH 20 KNOBS and 15 mini-toggle switches spanning its front panel, the Sig:X might at first glance appear daunting. But when you visualize the control layout as three sections, with the Lead channel above the Rhythm channel, and the Clean channel to the right, the amp’s basic functions are in fact quite easy to understand and operate. While each of the three channels offers a full set of familiar Treble, Middle, and Bass controls, the mini-toggles are the key to unlocking the amp’s flexibility and full potential. These mini-switches let you fine-tune and personalize the channel’s individual texture, dynamic response and voicing nuances, and the range of possibilities seems almost unlimited when you add-up all the switch combinations and multiply that by an almost infinite number of control pot variations.

The Power Shift mini-toggles greatly expand each channel’s range of dynamic response by shifting the amp’s output between 40 and 100 watts. But there’s more to the dual-power option than simply lowering the output power, the Power Shift switches are the gateway to VHT’s Enhance Mode and Dynamic Sensing Technologies as well.

Introduced in 1995, VHT’s Enhance Mode Technology utilizes a combination of tube and solid-state rectifiers to shift the voltage being fed to the output stage while also changing the amount of power supply filtering. “It’s called ‘Enhance Mode’ because there is no on/off switching of the rectifier circuits,” explains founder Steve Fryette. “In 100-watt mode, the solid-state circuit operates in parallel with the tube rectifier supply, so both circuits are essentially ‘enhancing’ each other. In 40-watt mode, the tube rectifier supplies the power tubes while the solid-state circuit feeds the regulated Dynamic Sensing preamp supply. The Dynamic Sensing feature varies the preamp tubes’ voltages in response to the player’s picking attack and the output level set by the Power Shift switch.”


WHILE THE SIG:X’s three channels are clearly labeled Clean, Rhythm, and Lead, each channel’s range of tones, textures and dynamic response is much broader than its name might imply. For example, with a P-90-equipped Les Paul Junior and the Clean channel engaged in 100-watt mode, the Sig:X/Deliverance cab half-stack can easily evoke a Hiwatt’s powerful punch, crashing spank and brilliant sheen. The amazing thing is these impressive tones can be duplicated quite closely by the Rhythm and Lead channels. That’s not the sort of range or capability you’d normally expect from channels that appear to be tailored more for higher-gain tones—and that only begins to highlight the amp’s impressive versatility. But the point isn’t to sound like a Hiwatt or any other classic amp, the Sig:X’s flexibility is the gateway to new sounds and textures—and your own signature tones.

Switching the Clean channel to 40-watt mode enhances the tactile response with a more resilient and expressive attack that’s further embellished by switching the voicing switch to the aptly named “Bloom” position. It’s all about feel here, and that’s where the Sig:X separates itself from the pack. The low-end can be plumped to pleasing perfection with the help of the fat switch, and engaging the boost switch increases the drive by 6dB for more preamp push.

The Lead and Rhythm channels also feature assignable Power Shift switches, and their channel-specific pre-gain voice switches provide contrasting tone-tailoring palettes. Again, both of these channels are capable of an amazingly wide range of impressive tones; it would take days to talk about them all. With humbuckers or single-coils, either channel is capable of tight clean and crunch tones as well as a vast array of searing lead tones. And with some help from the amazingly powerful and effective boost, gain and scoop switches, you should have no problem personalizing your own scooped-metal tones as well.


VHT’s SIG:X OFFERS an amazingly broad range of happening tones that seamlessly morph from channel to channel so effectively that it seems to transcend the narrow clean/crunch/burn limitations of a typical three-channel amp. And it forms an especially synergistic bond with VHT’s well mannered and musically balanced Deliverance 4×12 speaker cabinet. Whether you play classic rock, prog or metal, there’s a wealth of signature tones waiting here to be discovered.

Thanks to VHTAMP.com and Terry Buddingh for the review

VHT Sig:X Amplifier Head

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